Oil pressure controlled fuel valve, preferably for oil burners



Dec. 5, 1961 G; HANSEN 3,011,507

OIL PRESSURE CONTROLLED FUEL VALVE, PREFERABLY FOR OIL BURNERS Filed Jan. 2, 1957 ,A: J- 2572*" 26 A 26 15 i /4 2 L/ 28" E /9 7 f 8 7T 7 7 11 10 9 Z United States Patent 3,011,507 01L PRESSURE CONTROLLED FUEL VALVE, PREFERABLY FOR OIL BURNERS Gunnar Lyshdj Hansen, Elsmark, Nordborg, Als, Denmark, assignor to Danfoss veti ingenir Mads Clausen, Ale, Denmark, a Danish firm Filed Jan. 2, 1957, Ser. No. 632,088 Claims priority,. application Denmark Apr. 13, 1956 4 Claims. (Cl. 137-116) The invention relates to an oil-pressure controlled fuel valve, preferably for oil burners, said fuel valve consisting of a cylindrical container having one end closed by a main piston moved by the oil pressure against'spring action and opening and closing a cut-off valve which is mounted at the other end of the container and communicates with the discharge opening of the fuel valve.

Fuel valves of the aforesaid kind are known, but they have the drawback that they are opened by the cut-off valve as soon as the oil pressure attains a predetermined amount, regardless of the presence ofother conditions relating to'su'pplying fuel to the burner, for example, Whether -or not the fan of the oil burner has built up a sufficient air'pressure for'satisfactory combustion. In the installation of known oil burners this drawback may be relieved by the useof magnet valves which at a suitable timelag in relation to the starto-f the fan, open for the supply of fuel. This, however, means a complication and an increased cost of the installation.

' It is the object of the invention to provide an oil-pressure controlled fuel valve which in simple manner gives such a'desired, predetermined delayed action.

An essential feature of an oil-pressure controlled fuel valve according to the invention is that the main piston has a cylindrical extension which is provided with a coaxial hollow space having at least one opening to establish communication with the interior of the container. In the longitudinal direction of said hollow space is a looselyfitted spring-loaded valve body, which limits a closed chamber located in that end of the hollow space which is close to the cut-off valve, the valve body being adapted to open and close a passage leading through an auxiliary piston to that end surface of said piston which is remote from the interior of the cylindrical container.

As a result the opening movement of the cut-off valve is delayed, since the oil pressure, when the main piston is in the position closing the cut oif valve, forces the auxiliary piston away from the valve body and the oil flow is admitted through the passage in the auxiliary piston, whereby the building up of the oil pressure in the container is delayed until the valve body is displaced by the action of the spring, the oil seeping slowly along the cylindrical surface of the valve body into the chamber owing to the loose fitting of said body in said chamber and closing the passage through the auxiliary piston. 'Only when the oil pressure in the container attains a value such that the main piston is capable of overcoming the spring action to which it is subjected, does the piston move so as to open the cut-off valve. There is'thus a time lag between the building up of the oil pressure in the container and the opening of the cut-off valve.

In one embodiment of the fuel valve according to the invention the passage in the auxiliary piston is constructed as a movable sleeve, preferably coaxially disposed in the main piston, and subjected to spring action in the direction towards the valve body. 7

As a result, the cut-off valve will rapidly close when the oil pressure in the container drops,.for example, when the oil pump of the oil burner is disengaged, the movernent of the main piston by the action of the spring for closing the cut-oifvvalve causing the valve body to be removed from' the opening in the passage providedin the auxiliary piston, whereby the oil pressure in the container is further decreased, and the closing movement of the main piston is effected by its own spring action is accelerated so that the cut-off valve is rapidly closed. In another embodiment according to the invention, the springactivated movement of the auxiliary piston away from the valve body is limited by a powerful coil spring mounted coaxially between the auxiliary piston and a permanent stop in the casing proper, said coil spring having an extent axially which is less than the distance between that end surface of the auxiliary piston which is remote from the valve body and fixed stop when the cut-off valve is in its closed position.

As a result, the auxiliary piston is only capable of moving a predetermined distance for fixing the desired time lag, its movement being stopped by the powerful coil spring which furthermore mufl'les the noise caused by the vibrations of the auxiliary piston produced by pulsations in the oil pressure. I

In a preferred embodiment of the fuel valve according to the invention, the main piston is. designed as a sleeve valvein relation to return and by-pass passages opening into the cylindrical wall of the container and, by altering itsspring action, the pistonrnay be adjusted so as to regulate the voil pressure in the container and the pressure of the oil passing the cut-off valve to the burner nozzle of the oil burner.

As a result, the oil-controlled fuel valve may be manually adjusted at the desired oil pressure in the'discharge opening of the cut-off valve so as to act .not only as a cutoff valve but also as a pressure regulating valve.

The invention will be further described with reference to the drawing, which shows a section of an oil-pressure controlled fuel valve according to the invention.

In the drawing, one end of a cylindrical container 1 is closed by amain piston 2 moved against the action of a spring by means of the oil pressure exerted by the pump of an oil burner. The oil exerting the pressure is supplied through an inlet opening 3 connected through a pipe (not shown) with the oil pump of the oil burner. The main piston 2, which is subject to the action of a coil spring 24 mounted in the container opens and closes a cut-offvalve mounted in the other end of the container and communicating with the discharge opening 6 of the fuel valve. The main piston 2 has acylindrical extension 7 which is provided with a coaxial hollow space 8 with at least one communication open- 13 located at that end of the hollow space 8 which is close to the cutoff valve 5 and the valve body 11 is adapted to open and close a passage 14 leading through an auxiliary piston 15 to the end surface 16 of piston 15 which is remote from the interior of the cylinder 1. The auxiliary piston 15 may be in'the form of a movable sleeve, preferably coaxially disposed in the main piston 2 and subjected to the action of a comparatively weak coil spring 17 in the direction towards the valve body, 'said spring being inserted between the-end surface 16 and a closing memberlS which closes that end of the container 1 which is remote. from the cutoff valve and is provided with a seal ring 19 resting ing ofthecontainer by means of a locking ring 20 and is providedwith a long threadedv pin 21 that carries a They nut 22 which serves as a displaceable rest for the coil spring 24 so as to adjust its tension. The nut 22 is provided with a pin 23 received in a transverse slot 22' in the nut and being vertically movable in cylinder 1 in a vertical slot 23 in the cylinder wall to prevent the nut from turning, but not preventing its displacement along the pin 21 and by turning the closing member about its axis it is therefore possible to displace the nut 22 on the threaded pin 21. It will be understood that the pin 23 is but one possible means for preventing the nut 22 from turning and that any other convenient means may be employed for this purpose, including various means well-known in the art. The movement of the auxiliary piston 15 away from the valve body 11 is limited by a powerful coil spring 4 mounted coaxially between the auxiliary piston 15 and a permanent stop provided inside the container 1, for example the pin 21, and the coil spring 4 is of an axial extent less than the distance between the end surface 16 of the auxiliary piston 15 and the said permanent stop when the cut-off valve is in its closed position. The main piston 2 may be formed with a sleeve valve 25, the cylindrical wall of the container 1 being provided with openings 26 and 27. The openings 26 are adapted to be connected to the return pipes of the conventional fuel supply pump for the oil burner and the openings 27 are adapted to be connected to a by-pass or recirculation system. Admission to said openings may be controlled in varying degrees by the sleeve valve 25 in conformity with the position of the main piston 2. The main piston 2 is provided with a fiow opening 28 through which the oil may pass from the container interior to a space located between the mainpiston and the sleeve valve, which by alteration of the tension of the spring 24 may be adjusted to regulate the oil pressure in the container and the pressure of the oil passing the cut-off valve to the burner nozzle of the oil burner. Such regulation is effected so that one edge of the sleeve valve covers the openings to the return pipe more or less, whereas the other edge of the sleeve valve simultaneously covers the opening 27 for the by-pass pipe in varying degrees.

Under control of the cut-ofi valve 5 of the fuel valve a part of the oil, the quantity selected depending on the size of the burner nozzle, flows through the discharge opening 6 to the nozzle whereas any excess oil, if the oil firing installation is of the so-called two-flow type, flows through passages 28 in the spring-activated cutoff valve 2 to a storage tank (not shown). If the installation is of the so-called single-flow type, the oil is passed to re-circulation.

When the oil pressure in the interior of the fuel valve has reached a predetermined value after the starting of the pump, the spring-activated cut-off piston 2 is normally displaced, whereby the cut-off valve 5 uncovers the opening of the piping to the burner nozzle. However, in order to insure that the fan which supplies primary air to the burner nozzle delivers an air pressure sufiicient for a substantial combustion of oil before the cut-off valve 5 is opened, and to obtain a rapid closing of the cut-01f valve when the power supply to the oil burner is interrupted, the invention provides for delaying the openingmovernent of the cut-off piston 2 and accelerating the closing movement of the piston by means of a pressure drop which arises by opening an extra passage 14 in the cut-off pistonZ, the opening and closing of this extra passage being controlled by the pair of cooperating spring and oil pressure activated piston members 11 and 15 accommodated in the cut-off piston 2.

By alteration of the tension of the closing spring 24, the sleeve valve may be adjusted to regulate the oil pressure in the container 1 and the pressure exerted by the oil fiowingfl through the cut-off valve 5 to the burner nozzle. Thesa-id regulation is eifected by reason of the fact that one edge of the sleeve valve 25 covers the openings 26 to a varying extent, whereas the other edge of the sleeve valve 25 simultaneously uncovers or covers the openings 27 in varying degrees.

The delay obtained by such regulation is of the order of 2-12 seconds, which in practice has been found sufficient to ensure substantial combustion without formation of soot during the start of the oil burner and complete ventilation of the combustion chamber of the oil burner prior to a renewed start. The above-described valve has two important advantages in operation, viz.:

(a) A time delay in the opening of the cut-off valve,

(12) A momentary cut-off of the oil to the burner by falling oil pressure.

Thus, a main element of the valve is the valve body 11. When the valve isconnected in a fuel supply system, at the start of the pump and the blower, the cutoff valve 5 is closed, the extension 7 of the main piston 2 abuts against the discharge opening 6, and the valve body 11 abuts against the auxiliary piston 15, thereby closing the passage 14. As the oil pressure builds up, the auxiliary piston 15 is moved upwards and thus opens the passage 14 and provides a drop in the oil pressure, until the valve body 11 slowly, and under the action of its spring 12, moves upwards and finally closes the mouth of the passage 14. Thereafter, the oil pressure again builds up and reaches a value which is suflicient to move the main piston 2 and by this movement the cut-oif valve is opened. But this will first occur only after a delay determined by the time it takes for the valve body 11. to move from its position at the start in which it closes the mouth of the passage 14 or until it, after a delay of 2-12 seconds, has overtaken the upward moving auxiliary piston 15, the upward movement of which is limited by the spring 4. When the pump and the blower stop, the cut-off valve 5 is open and the valve body 11 closes the pasasge 14, but at the beginning of the decay of the oil pressure, the main piston 2 will move downwards and the valve body '11 will be stationary in relation to main piston 2, While the auxiliary piston 15 will not (owing to the weakness of the spring 17) follow the main piston 2, and by the mutual movement between the valve body 11 and the auxiliary piston 15 the mouth of the passage 14 will be. opened, providing a further decay in the oil pressure, this decay accelerating the closing of the cut-off valve 5.

The valve body 11 will, as pointed out above, and especially during the first moments, substantially follow the main piston, because the spring 12 can move the valve body 11 only to the degree the oil can penetrate the narrow annular space between the valve body 11 and the walls of the inner space in the extension 7. The oil pressure in the container of the fuel valve, when the oil burner is started, cannot rise to the predetermined value at which the fuel is to be conducted to the burner nozzle before the two coworking members 11 and 15, in a predetermined. small space of time, for instance 2-12 seconds, have opened the passage 14, and when the oil burner is stopped, the decay of pressure is augmented by another opening of the passage 14 to accelerate the closing of the cut-off valve.

The delay at the start is utilized to procure a vigorous ventilation of the burner chamber to insure against explosions, and the acceleration of the closing at the stop of the pump is utilized to prevent any appreciable amount of fuel from being injectedinto the burner chamber after the pump and the blower have decreased their pressure.

Although the foregoing'specification describes a special embodiment ofthe oil-pressure controlled fuel valve according to the invention, said embodiment does not limit the scope of the invention, said scope being exclusively determined by the appended claims.

, What I claim and desire to secure by Letters Patent 15: p 1. An oil pressure control valve for an oil burner adapted to receive oil from a pump and to supply the oil to the burner comprising, in combination, a hollow cylindrical container having a closed end and slidably receiving a main piston responsive to the oil pressure in the valve, a spring acting upon said main piston against said oil pressure, the opposite end of said container being formed wtih an inlet opening and with a discharge opening, said main piston forming with said discharge opening, a cut-off valve for controlling the flow of fluid through said discharge opening, said main piston being formed with a cylindrical extension formed with a coaxial hollow space having at least one opening providing communication with the interior of the container, a loosely fitted valve body in said hollow space movable in the longitudinal direction of the space, an auxiliary piston having an axial bore providing communication between said hollow space and a second space in said container at the end of said main piston remote from said cylindrical extension, said valve body being adapted selectively to open and close said bore of said auxiliary piston, said valve body being spring-loaded in the direction of said bore and said auxiliary piston being re siliently urged in the direction of said hollow space, said container being formed with at least one return portion communicating with said second space for withdrawal and return of oil flowing to said second space through said bore, and stop means limiting the movement of said I auxiliary piston away from said valve body.

2. A fuel valve as defined in claim 1, wherein said container is formed with an adjustable stop member and said spring is a coil spring mounted coaxially between the main piston and said stop member inside the container, and said stop means is a coil spring of an axial extent less than the distance between an end surface of the auxiliary piston remote from the discharge opening and the stop member when the cut-off valve is in its closed position.

3. A fuel valve as defined in claim 1, wherein said container is formed with lateral by-pass ports and said main piston is positioned selectively to vary the area of said return and by-pass ports, whereby by altering the spring action to which the main piston is subjected it may be adjusted to regulate the oil pressure in the container and the pressure of the oil which leaves the outlet opening. a

4. A fuel valve as defined in claim 1, wherein the auxiliary piston is slidably mounted coaxially in said main piston and is resiliently urged by a coil spring urging said auxiliary piston in the direction of said hollow space.

References Cited in the file of this patent UNITED STATES PATENTS 2,036,489 Murphy Apr. 7, 1936 2,391,790 Martinsson Dec. 25, 1945 2,749,935 Heard June 12, 1956 2,779,347 Munroe Ian. 29, 1957 t 

